Build 38862, Steam, Windows 10
Villagers are able to create walls even when their construction path is obstructed by other villagers, “trapping” them inside.
One of my villagers got stuck inside a wall created by my other villagers. I could not move it from there, so I started attacking the enemy town center.
Similar scenario, but this time a town center was built and it was preventing one of my villagers from moving correctly (compared to the first bug encountered with walls, this villager was able to slightly move from his position). Eventually, such a villager was able to escape, but not by his own; I had to manually command him to move, multiple times: 
Babylonian villagers built fortified walls in the place of another villager:
This is very serious, so I hope it gets fixed in future updates.